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utils: Add SDP parser
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‎Makefile.in‎

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@@ -224,6 +224,7 @@ TEST_OBJS = $(COMMON_OBJS) \
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test/test_tv.o \
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test/test_net_udp.o \
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test/test_rtp.o \
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test/test_sdp_parser.o \
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test/run_tests.o
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DEP_FILES_2 = $(REFLECTOR_OBJS) $(TEST_OBJS) $(ULTRAGRID_OBJS)

‎configure.ac‎

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@@ -3501,6 +3501,7 @@ if test "$build_default" != no || test "$req_files" = all; then
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src/capture_filter/ratelimit.o
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src/capture_filter/split.o
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src/capture_filter/temporal_3d.o
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src/utils/sdp_parser.o
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src/video_capture/aggregate.o
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src/video_capture/import.o
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src/video_capture/switcher.o

‎src/utils/sdp_parser.cpp‎

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/**
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* @file utils/sdp_parser.cpp
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* @author Martin Piatka <[email protected]>
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*/
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/*
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* Copyright (c) 2025 CESNET, zájmové sdružení právnických osob
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, is permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* 3. Neither the name of CESNET nor the names of its contributors may be
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* used to endorse or promote products derived from this software without
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* specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING,
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* BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
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* AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
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* EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
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* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
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* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
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* EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "sdp_parser.hpp"
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#include "utils/string_view_utils.hpp"
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Sap_packet_view Sap_packet_view::from_buffer(const void *buf, size_t size){
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Sap_packet_view ret;
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std::string_view sap(static_cast<const char *>(buf), size);
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if(sap.empty()){
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return ret;
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}
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ret.flags = sap[0];
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sap.remove_prefix(1);
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ret.version = ret.flags >> 6;
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uint8_t auth_len = 0;
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if(sap.empty())
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return ret;
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auth_len = sap[0];
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sap.remove_prefix(1);
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//TODO error check length
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ret.hash = sap[0] << 8 | sap[1];
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sap.remove_prefix(2);
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//TODO error check length
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ret.source = sap.substr(0, 4);
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sap.remove_prefix(4);
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//TODO error check length
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sap.remove_prefix(auth_len);
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if(sv_is_prefix(sap, "v=0")){
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//RFC says that the payload type is optional if it's sdp and
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//that it should be detected by the presence of v=0
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ret.payload_type = "application/sdp";
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ret.payload = sap;
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} else {
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auto null_idx = sap.find('\0');
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if(null_idx == sap.npos){
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return ret;
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}
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ret.payload_type = sap.substr(0, null_idx);
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ret.payload = sap.substr(null_idx + 1);
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}
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ret.valid = true;
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return ret;
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}
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Sdp_view Sdp_view::from_buffer(const void *buf, size_t size){
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Sdp_view ret;
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std::string_view sdp(static_cast<const char *>(buf), size);
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if(sdp.empty()){
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return ret;
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}
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while(!sdp.empty()){
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auto line = tokenize(sdp, '\n');
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if(line.empty())
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continue;
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if(line.back() == '\r')
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line.remove_suffix(1);
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auto eq_idx = line.find('=');
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if(eq_idx == line.npos){
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continue;
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}
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auto key = line.substr(0, eq_idx);
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auto val = line.substr(eq_idx + 1);
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if(key == "c"){
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if(ret.media.empty()){
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ret.connection = val;
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} else {
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ret.media.back().connection = val;
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}
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} else if(key == "a"){
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auto attrib = tokenize(val, ':');
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auto attrib_val = tokenize(val, ':');
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if(ret.media.empty()){
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ret.session_attributes.push_back({attrib, attrib_val});
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} else {
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ret.media.back().attributes.push_back({attrib, attrib_val});
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}
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} else if(key =="s"){
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ret.session_name = val;
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} else if(key == "o"){
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ret.origin = val;
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} else if(key == "m"){
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ret.media.emplace_back();
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auto& medium = ret.media.back();
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medium.media_desc = val;
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}
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}
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ret.valid = true;
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return ret;
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}
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Rtp_pkt_view Rtp_pkt_view::from_buffer(void *buf, size_t size){
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Rtp_pkt_view ret{};
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if(size < 12)
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return ret;
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auto charbuf = static_cast<unsigned char*>(buf);
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uint8_t version = charbuf[0] >> 6;
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bool padding = charbuf[0] & (1 << 5);
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bool extension = charbuf[0] & (1 << 4);
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ret.csrc_count = charbuf[0] & 0x0F;
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ret.marker = charbuf[1] & 0x80;
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ret.payload_type = charbuf[1] & 0x7F;
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ret.seq = charbuf[2] << 8 | charbuf[3];
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ret.timestamp = charbuf[4] << 24 | charbuf[5] << 16 | charbuf[6] << 8 | charbuf[7];
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ret.ssrc = charbuf[8] << 24 | charbuf[9] << 16 | charbuf[10] << 8 | charbuf[11];
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size_t data_offset = 12 + ret.csrc_count * 4;
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ret.data = &charbuf[data_offset];
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ret.data_len = size - data_offset;
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ret.valid = true;
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return ret;
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}

‎src/utils/sdp_parser.hpp‎

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/**
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* @file utils/sdp_parser.hpp
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* @author Martin Piatka <[email protected]>
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*/
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/*
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* Copyright (c) 2025 CESNET, zájmové sdružení právnických osob
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, is permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* 3. Neither the name of CESNET nor the names of its contributors may be
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* used to endorse or promote products derived from this software without
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* specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING,
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* BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
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* AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
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* EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
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* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
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* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
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* EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef SDP_PARSER_HPP_cccb52235120
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#define SDP_PARSER_HPP_cccb52235120
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#include <string_view>
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#include <vector>
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#include <cstdint>
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#define SAP_FLAG_COMPRESSED (1 << 0)
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#define SAP_FLAG_ENCRYPTED (1 << 1)
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#define SAP_FLAG_DELETION (1 << 2)
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#define SAP_FLAG_IPV6 (1 << 4)
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struct Sap_packet_view{
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uint8_t version;
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uint8_t flags;
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uint16_t hash;
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std::string_view source;
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std::string_view payload_type;
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std::string_view payload;
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static Sap_packet_view from_buffer(const void *buf, size_t size);
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bool isValid() const { return valid; }
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bool isCompressed() const { return flags & SAP_FLAG_COMPRESSED; }
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bool isEncrypted() const { return flags & SAP_FLAG_ENCRYPTED; }
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bool isDeletion() const { return flags & SAP_FLAG_DELETION; }
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bool isIpv6() const { return flags & SAP_FLAG_IPV6; }
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bool valid = false;
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};
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struct Sdp_attribute{
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std::string_view key;
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std::string_view val;
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};
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struct Sdp_media_desc{
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std::string_view media_desc;
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std::string_view title;
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std::string_view connection;
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std::vector<Sdp_attribute> attributes;
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};
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struct Sdp_view{
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std::string_view origin;
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std::string_view session_name;
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std::string_view session_info;
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std::string_view connection;
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std::string_view session_time;
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std::vector<Sdp_attribute> session_attributes;
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std::vector<Sdp_media_desc> media;
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static Sdp_view from_buffer(const void *buf, size_t size);
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bool isValid() const { return valid; }
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bool valid = false;
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};
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struct Rtp_pkt_view{
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bool marker;
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uint8_t payload_type;
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uint16_t seq;
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uint32_t timestamp;
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uint32_t ssrc;
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//uint32_t *csrcs;
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size_t csrc_count;
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void *data;
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size_t data_len;
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static Rtp_pkt_view from_buffer(void *buf, size_t size);
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bool isValid() const { return valid; }
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bool valid = false;
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};
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#endif

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